He shoulda been happy with that, it's not like there were a lot more of them coming.But seriously: It is THE Spock movie. Co-starring Kirk (even if he does have more screen time).
TWOK & TSFS were Kirk's movies. TUC also put the major arc on Kirk, tying up his grief and misplaced anger.
Character wise, I feel like TVH and TFF were the weakest but they had moments to shine. TVH was mostly about the message and laughs, but Spock did have his journey back to embracing his human side. That's important, without question. It's just more of a spice in the mix than the driver of the plot. TVH is a plot driven movie. However, serious props to Harve Bennett for finally tying up Spock and Sarek's story. That was actually my favorite part of the film. Actually from the trial to the credits, man that movie really hits me. The rest I can take or leave.
TFF: Kirk, I guess, who goes from not having a family to realizing Spock and McCoy are his family. This didn't seem like news to me. The strongest arc, and the driver of the plot is Sybok. Nobody else has an arc. You can argue McCoy, but his begins and ends in the same scene. We never knew he was dealing with the guilt he was carrying. Spock's was a non-starter. Sybok was dealing with outdated information.
Having said that, all 6 films did try to add to and deepen the characters in various ways, at least the Big 3.